Drop voltage after connect firmata


My project is mainly a push button box… The goal is once the user pushes one of the 3 push buttons the LED of the correspondent push button should light up, in order to confirm that the button was pushed. Unfortunately I’m having some problems with the implementation.
When I connect the Arduino board to the PC using the USB connection (without load any script), the circuit works as expected… once I push one of the push buttons the LED lights up with the expected light intensity (Figure 1). Nevertheless, once I upload the fimata file to the Arduino board and then my own Python script and then press one of the buttons, the LED is turned on but with a very low intensity (Figure 2). At the moment I’m not able to understand what is wrong with the implementation, why the LED doesn´t present the standard intensity.
Enclosed you also may find the implemented circuit (Figure 3).

Thank you in advance!

I wasn't able to get your picture of code to compile in Processing...

Do the pins default to OUTPUT when firmata is loaded?